Abstract
A biomedical β-type Ti-13Nb-13Zr (TNZ) (wt pct) ternary alloy was subjected to severe plastic deformation by means of hydrostatic extrusion (HE) at room temperature without intermediate annealing. Its effect on microstructure, mechanical properties, phase transformations, and texture was investigated by light and electron microscopy, mechanical tests (Vickers microhardness and tensile tests), and XRD analysis. Microstructural investigations by light microscope and transmission electron microscope showed that, after HE, significant grain refinement took place, also reaching high dislocation densities. Increases in strength up to 50 pct occurred, although the elongation to fracture left after HE was almost 9 pct. Furthermore, Young’s modulus of HE-processed samples showed slightly lower values than the initial state due to texture. Such mechanical properties combined with lower Young’s modulus are favorable for medical applications. Phase transformation analyses demonstrated that both initial and extruded samples consist of α′ and β phases but that the phase fraction of α′ was slightly higher after two stages of HE.
Highlights
A near b-type ternary TNZ alloy was subjected to the hydrostatic extrusion (HE) process at room temperature (RT) in two stages, and its effect on mechanical properties, microstructure, and phase transformation behavior was investigated with an aim of producing a high-strength, low-modulus, biocompatible titaniumbased implant material
It should be noted that the surface of the billets has no macroscopic defects, which demonstrates the smooth flow of TNZ alloy during HE
The near b-type TNZ alloy was subjected to HE in two passes with a total true strain of 2.49, and its effect on microstructure, mechanical properties, and phase transformation was studied
Summary
THE major requirement for metallic materials in biomedical applications includes good mechanical properties, i.e., sufficient strength and ductility, low Young’s modulus, high wear resistance and fatigue strength, as well as corrosion resistance and biocompatibility (no adverse effect to a human body).[1,2,3] Among metallic materials used in biomedical applications, titanium and its alloys are attractive due to their relatively low Young’s modulus (compared to stainless steels and Co alloys), high-strength/weight ratio, superior corrosion resistance, and excellent biocompatibility.[4,5,6] titanium and its alloys are better candidates for load-bearing biomedical implants than polymers and ceramics due to their high mechanical strength and fracture toughness.[7]. One of the efficient ways to improve the mechanical strength is to apply severe plastic deformation (SPD) methods to decrease the grain size to the ultrafine-grained (UFG) range (i.e., below 1 lm) in accordance with the Hall–Petch relationship.[20,21,22,23,24] To effectively reduce the grain size, SPD methods, such as accumulative roll bonding,[25] high pressure torsion (HPT),[26] and equal channel angular pressing,[27] can be used Besides these typical SPD methods, hydrostatic extrusion (HE) is an efficient way of grain refinement. The previous studies demonstrated that its efficiency in terms of refinement depends on the material features and processing conditions.[29,30,31] In this study, a near b-type ternary TNZ alloy was subjected to the HE process at room temperature (RT) in two stages, and its effect on mechanical properties, microstructure, and phase transformation behavior was investigated with an aim of producing a high-strength, low-modulus, biocompatible titaniumbased implant material
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
